The playback speed on youtube.com can be manipulated by using keyboard shortcuts < and >.
However, on my MacBook only the > for increasing playback speed seems to work while < does nothing.
What do I have to do, to make < work as well? Is there a way to decrease playback speed with another key?
Edit: According to the keyboard shortcut list on YouTube Shift+, and Shift+. should increase/decrease playback speed as well. Both combinations do not work either.
Edit2: As @Tir Dy pointed out, it works in Firefox.